Method of making pottery molds



1948. L. P. REE sE METHOD OF MAKING POTTERY MQLDS 4 Sheets-Sheet 1 Filed Oct. 2, 1943 INVENTOR' Law/s F. REESE ATT Aug. 24, 1948. R REESE 2,447,598

METHOD MAKING POTTERY MOLDS Filed Oct. 2, 1943 4 Sheets-Sheet FIG. 6

IN VEN TOR. LEW/5 R REESE ATTZ1 RNEY.

Aug. 24', 1948. V p SE 2,447,598

METHOD OF MAKING POTTERY moms Filed Oct. 2, 1943 4 Sheets-Sheet 5 Fla. 5

INV LEW/s F. REEsE BY 7 7 A TZJRNE y.

Aug. 24, 1948- L. P. REESE 2,447,593

' METHOD OF MAKING POTTERY moms Filed Oct. 2, 1943 4'Sheets-Sheet 4 INVENTOR.

LEW/5 P. REESE FIG. 7

Patented Aug. 24, 1948 UNITED STATES PATENT .rrice 2' Claims.

This invention relates to methods for manufacturing plaster molds such as those used in the production of pottery dinnerware and. the like.

Potteryware of the above described, class is now being made on high-speed automatic. form-- ing machinery in mass production fashion. This kind ofequipment requires many more original and replacement molds for a given shape or shapes than would ordinarily be required in manual production. This is due to the large mold capacity of the machinery and the shorter recycling period which uses up the mold faster although there, is no reduction in the ware yield per mold. Furthermore, machine molds must be. accurately made and are held to closer tolerances than molds used in hand jiggering particularly in regard to seating surfaces by means of which the molds are supported and centered during fabricating operations.

The average mold shop, where the molds are made, is primarily a manual institution, geared to manual production methods and operating atv manual production speeds, with customary manual efficiency. The increased and more exact demands ofautomatic production has given rise to the problem of how to make molds faster, better and more economically than heretofore in order to avoid depreciation of the savings afforded by mass production economy in the manu facture of the ware. i

The present invention has for its principal object the provision of new and improved mold making methods for increasing the output of the mold shop, enabling a higher degree of precision in the manufacture of molds and the introduction of economies intended to lower the overall cost of making molds. Other objects are to conserve manpower and reduce the need for skilled craftsmanship in the manufacture of molds; to improve and expedite moldmaking procedure and processes and to place the manufacture thereof on a mass production basis ideally suited to supply the demands of mass producing automatic pottery ware forming machinery.

One of. the advantageous features of this invention resides in the fact that much of the skilled craftsmanship of the manual method. is

eliminated andunskilled labor may, to a great.

extent, be employed.

Another advantageous feature is that the invention will enable the continuous production of molds and the output within a given period.

can be accurately estimated and varied to meet requirements. I

Another advantageous feature is that each Worker may learn and become proficient ata particular operation ascontrasted with procedure in the ordinary hand shop where each mold maker is a. skilled, craftsman. and does all the necessary work himself.

Still another advantageous. feature is that the procedure may be standardized which is an improvement over previous practice where each craftsman made the molds according to his own formula.

To implement the process, I have provided fora moving production line which is a new and different. idea insofar as the manufacture of products of this class are concerned. The work is brought to the operators who are no longer required to lift, carry and, perform other non-i productive operations. but may apply their efforts wholly to mold making which enables. greater concentration on and, more rapid com pletion of the. work. The matter of mixing the ingredients and supplying them to the moving. production. line is carried out. in cor-ordinated,

semi-automatic. fashion, the p pQrt oning. and:

mixing of ingredients being automatically controlled so that the procedure, as. well as the mix, may be standardized and uniform for each $11G?" cessive batchthus insuring that the porosity.

density, hardness and strength of the molds will be. held to optimum and uniform specifications.

In the drawings:

Fig- 1 is a plan View of the preferred form of apparatus for carrying out my invention.

Fig. 2 is aside elevation of the driving appaeratus for the conveyor of Fig. 1.

Fig. 3 is a vertical section through the mold conveyor with a fragment thereof shown in per-- spective.

Fig. 4.- is an elevationof the. apparatus of Fi Fig. .5 is a front elevation of the apparatus for supplying and mixing the. ingredients.

Fig. 6 is a plan view of the receptacle. stabilizer located at. the mixing station.

Fig. 7- is. a side elevation, with some of the parts removed, of the apparatus. for measuring the. solid ingredients of the mixture.

Withv reference. to, Fig- 1, l is. a circular table.

whose, upper surface is preferably made of WQQd or. composition. having. a low coefficient of. fIi'Qr tion so. that the mold cases, will not slide and is. divided into inner and outer circumferentialzones 2. and 3 by a. vertical. circular rib 5.. The table, Fig. 3 is supported on. a mono-rail 5. resting.

on several flanged wheels 6 supported from the floor on bearings T. The wheels are spaced several feet apart, but the number and location of them depends upon the diameter of the table, however. it is desir d that alternate wheels be turned so that the flan e is reversed thus tend n to m nimize any tendency of the table to shift ra ially on the su ports.

The ra l is attached to a c rcular I beam 8 from which b ac s and struts 9 angle u wardly to su ort the tabl too near t e inner a d outer per meters. To rotat the tabl 9, cab e In is wound arou d th mo o-ra l and a l 1 I passed around pull ys 2 a d '3 f he drivi g echanism, Fi 3. located a on s e the struc re. O e pul ey s hi her than the other so that t e cable w ll not rub wh re it crosses. and is driven by m ns o a mo or l4 u h vari le s ed tra sm on l5 and ch in dr ve I50 m ch m is o l v cl d by a protective cover 1 1) as lustra ed in Fi 4,

In its commerc al fo m. the tabl s fe ably at, least 50 fe t in d ame er but this fi ure i gflh'inct tn variation 'i'r satisfy sh r and ot er reouirements. The table too is made of am e width to accomm ate e v r ous i ems to be placed thereon and t p mit the wo k to b exp d t ou y e for d wit o t cr wdi v It s desired tha the tab e ro ate slow y. that is to say to cornnle -o one revolu on in n w ere between and 50 minutes depending on the diamet r a d the nature of the work a d to rota e continuously without interruption for successive cycles.

The too surface 3 of he table between the center rib and the inner pe meter rece ves and sup orts the separable mold cases which may vary in number depending on the diameter of the table and the size of the cases. The cases may be diversified for making a diverse production as illustrated by flatware mold case l6, Fig. 4 and holloware mold case I1.

Starting at the 0 position, Fig. 1, the interior of the case I! whose upper and lower halves are separated to expose the molding cavity, is soaped in conventional fashion as it travels past an operator or operators whose working range extends up to about the 45 position. It is customary to wipe the interior after it has been soaped and this may be done in this zone. The next zone, which may extend for approximately 10 more of rotation of the table up to about the 55 position is where the cases are reassembled in consecutive order by another operator. From the 55 position to the 110 position of the table is where the liquid plaster is poured into the mold cases and the mold shaken to settle the plaster and remove occluded air. Liquid plaster is supplied in containers or receptacles I 8 carried by a hoist l9 from a curved overhead section monorail on a radius with and concentric to the table in this zone, the topic of filling the containers with liquid plaster being discussed hereinafter.

Those cases requiring cores or sinkers, such as used to form the cavity in the base of flatware molds, are fitted with these devices between the 110 and 120 position of the table after the case has been filled and the plaster shaken down. Between the 120 and 130 positions the top of the case is scraped to smooth off the bottom surface, of the mold, and sinkers may be removed here or further on. At the 270 position the sections of the cases are knocked apart, and the molds removed and placed on the opposite or outside surface 2 of the table. From the 270 position around to the 0 position the interior of the cases are cleaned out by brushing and wiping and exposed to the drying influence of the air preparatory to soaping to complete the cycle. While the zones have been specified as extending between certain limits, it will be understood that these are arbitrary figures for the purpose of explaining the sequence of operations and the zones may be longer or shorter than given depending on the speed of rotation of the table and the time interval that may be safely allotted to the performance of any one of the operations described.

The molds M which are on the outside of the table travel around to a finishers bench 2| where they are removed one after the other and placed on a finishing machine 22 which trues up the bottoms and seating surfaces after which they are put back on the table and are carried to an oiling position defined by a revolving table 23. Here, the molds are dipped in a tank 24 of oil and set on table 23 to drain. When the oil has soaked in they are removed and placed on the shelves of monorail cars 23 to be carried to storage bins 25 or directly to the mold exchanging station of the mass producing ware forming machinery. Any molds which require further trimming may be allowed to remain on table I to be carried around again to the trimming station.

The various operations described are performed manually by different operators stationed at the zones mentioned. Each operator is an expert at his assigned task and through repetition becomes highly proficient. As the chi-- ciency oft-he operators increase, the speed of rotation of the table may be advanced to thereby raise production speed to its maximum value.

With regard to the apparatus for preparing the liquid plaster of which the molds are formed, it is well-known that plaster when mixed with water will set up in a short space of time and therefore I prefer to mix the materials in separate batches and in accordance with the requirements of the production line. I also prefer that the materials be mixed according to a predetermined formula and that the proportions be accurately measured and the quantities thereof and mixing time be accurately controlled, so as to produce an optimum mixture which will be uniform for sucessive batches.

For example, the receptacle 1 8 may have a 15 gallon capacity in which is mixed 8 gallons or 60 pounds of water and pounds of plaster, preferably under vacuum and for a period of 2 to 3 minutes, the plaster being allowed a soaking period of 3 minutes after it is emptied into the water. Vacuum is preferably applied for not less than two minutes While the ingredients are being mixed to thereby expedite the removal of occluded air, however, this step may, if desired be omitted.

When an empty receptacle is returned by hoist is to be refilled, the operator disengages the bucket from the hoist and immerses it in a wash tank 26, Fig, 1, to clean the interior of any residue from the preceding batch. The receptacle is then placed in upright position on the left end of a vi y n y r 2 Fig. 5, and pushed to the right to a position below nozzle 28. A measured quantity of water is discharged into the receptacle by turning control handle 29 to a position where passages 30 and 3| in valve disc 32 establish communication between tank pipe 33 and 5. nozzle 28-t0 thereby empty overhead tank 34. As the water level drops in the tank, the level-of float drops, switch 36' normally held closed by actuating pin. 31, opens and de-energizes circuit 38 to solenoid 39 and permitting the solenoid spring to raise valve stem toopen valve 5 l in water main 52. When the tank is empty, the operator throws the control 29 to a position where passage 3t establishes communication between the-water main 52 and pipe 33 to thereby fill the tank. When the. float 35: has risen to a pre-arranged level, switch 36 is closed and circuit 35 energized to. actuate the solenoid and shut-off valve 5|.

The quantity of water in tank 5 may be varied by adjusting the position of the float 3-5 or the position of the switch. A by-pass 42 is for equalizing pressure on opposite sides of the valve. The circuit has a manual switch 43 for push-button control.

After the measured quantity of water has been discharged into the receptacle, it is moved to a position below the outlet end of tube 53. This tube leads upwardly to a large bin 54 provided with a screen top 55, Fig. 1, and vibrator 56 thereon. A conveyor 51, Fig. 4, located adjacent the bin or hopper delivers sacks of plaster thereto from a source of supply to be opened and dumped through the screen into the bin.

A measured quantity of plaster is fed through the tube by raising the control rod 53, Figs. 5 and '7, loosely inserted in guide M which closes switch 59 and energizes circuit 60 to motor 6| which rotates an impeller 62 inside the tube and causes the pulverized plaster to flow through the outlet Whose gate 53 has been swung to open position by the raising of rod '58. The receptacle rests on the rollers of a section 64 of the gravity conveyor which is supported independently of the other sections on the platform frame 65 of a weighing scale, see Fig. 6. A pushrod 65 connected to one of the lower levers 61 is attached to an overhead beam 58 with which the balanced weight 45 is associated. When the amount of plaster for which the scale is set tips beam 68, a keeper it! drops down and permits latch ll to slide forward which permits the gate to drop by gravity to closed position. Rod 58 also drops down to its original position thus opening switch 58 and discontinuing the flow of plaster through the outlet. Latch H is pivotally connected to an arm 45 formed as part of a pivoted bracket 4! around tube 53. The bracket has an actuating arm 48 pivotally received between set collars 49 on rod 58. When the rod is raised latch H is reset.

The receptacle is moved from the position below tube 53 to a position below mixer all and after a three minute interval (this interval may vary depending on the mix), the operator grasps frame l3 and pulls it down until the circular cover l4 rests firmly in leakproof sealed relation with the rim of the receptacle. The inside of the cover is lined with rubber or the like to effect the seal and has a vacuum port l5, connected by a valved pipe 16 and flexible conduit 16' to a tank l1 which is connected by pipe 18 to a motor driven evacuator 18a. 19 is the agitator shaft which passes through a bearing in frame 13 and the cover 14 and is provided with blades to be driven by vertical motor 8| inverted on frame E3 to mix the materials in the receptacle. The frame i3 is supported for vertical movement in guide 82 and is counterbalanced by weights 83 vertically slidable on guides 84 and connected by cable 85 to frame 13.

After the cover is seated on the receptacle, the

operator sets timer 8!; by means. of dial 81 to cause the deenergization of circuit 88 after a given period of time has elapsed, the turning of the dial acting to energize the circuit and cause solenoid 90 to open'valve ill in vacuum line 16' to place the interior of the receptacle under vacuum and also energize signal lamp 92. Being a conventional form of timer provided with a double set of controls the other dial Bl is turned to a given position which acts to energize circuit 83- either simultaneously with, subsequent or prior to: the. energization of circuit 88 to start motor 8!; and they mixing operation and to illuminate signal lamp 9.5;. Vacuummay be discontinued before or after mixing ceases which for example, may last for a period of three minutes for a batch of the proportions described. When the time has elapsed, the vacuum line is automatically shut off by the timer and mixing discontinued which also de-energizes the signal lamps to thereby indicate to the operator that the batch is done. After frame 13 is lifted, the receptacle is moved to the right on the gravity conveyor and pivotally connected to the hoist by trunnions 98 and the receptacle lifted and transported to the pouring station where it is moved alon with the cases and tilted by handle and liquid plaster poured through spout 91 into the open tops of the cases as hereinbefore described.

To prevent rotation of the receptacle whilst the material is being mixed therein, it is wedged between a pair of vertical rollers 99, Fig. 6, and lug loll secured to the base of the receptacle is aligned with a notch lfll in stabilizing bar H32 pivotally connected at I03 to the conveyor frame and latched by dog IM against movement. The receptacle is thus held against rotating during the mixing operation and is released thereafter by unlatching and swinging the stabilizer bar back out of the way.

I claim:

1. The method of forming articles from plaster, which comprises placing a plurality of molds on an annular rotatable table, continuously rotating said table to repeatedly carry the molds through a series of zones, and while said table is rotating, feeding liquid plaster to said molds in one zone in the path of movement of the molds, permitting the plaster to solidify in the molds in another zone adjacent said first mentioned zone, opening the molds and removing the plaster articles therefrom in still another zone and closing the molds preparatory to receiving another charge of liquid plaster, placing the plaster article removed from its mold on said table in a position radially outwardly of its mold, thereby conveying the plaster article to a finishing zone, and finishing the article in said zone.

2. The method of forming articles from plaster, which comprises placing a plurality of molds on an annular rotatable table, continuously rotating said table to repeatedly carry the molds through a series of zones, and while said table is rotating, feeding liquid plaster to successive molds in one zone in the path of movement of the molds, permitting the plaster to solidify in the molds in another zone adjacent said first mentioned zone, opening the molds and removing the plaster articles therefrom in still another zone, reconditioning the molding surfaces in another zone, and closing the molds preparatory to receiving another charge of liquid plaster, placing the plaster article removed from its mold on said table in a position radially outwardly of its mold, thereby conveying the plaster article to a. finishing zone, and finishing the article in said zone.

LEWIS P. REESE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Jayne June 28, 1859 Jones Sept. 11, 1866 Doble Aug. 16, 1904 Crichfield Dec. 26, 1905 Number 

